Dishwasher appliances and methods for operating appliances

ABSTRACT

Dishwasher appliances and methods for operating appliances are provided. A method includes activating a drain pump to operate at a first speed, and ascertaining a dry drain status for the drain pump after a first speed drain time. The method further includes performing a deactivation routine when the dry drain status is positive, the deactivation routine comprising deactivating the drain pump. The method further includes performing a secondary drain routine when the dry drain status is negative, the secondary drain routine comprising activating the drain pump to operate at a second speed, the second speed greater than the first speed.

FIELD OF THE INVENTION

The present disclosure relates generally to dishwasher appliances, and more specifically to methods and apparatus for operating drain pumps of dishwasher appliances which balance efficient draining requirements with quiet operation desires.

BACKGROUND OF THE INVENTION

Dishwasher appliances generally include one or more pumps, such as a wash pump and/or drain pump. The wash pump can circulate liquid throughout a wash chamber of the dishwasher, for washing or rinsing items contained therein. The drain pump can remove liquid from the wash chamber of the appliance. For example, liquid can collect in a sump disposed at a bottom of the wash chamber during operation of the dishwasher appliance and the drain pump can be operated to urge such liquid from the sump to a drain where the liquid can flow out of the appliance.

In general, it is considered desirable for a dishwasher appliance to operate quietly. The noise level generated by the pumps is critical to such quiet operation. However, many dishwasher appliances are installed into environments which, for example, have undesirable draining conditions. It is thus critical that the drain pump in particular operate at a sufficient level to facilitate complete draining, even in such undesirable situations. This level, however, can result in louder than desired noise generation.

Accordingly, improved dishwasher appliances and methods for operating dishwasher appliances are desired. In particular, dishwasher appliances and associated methods which balance desires for quiet operation with complete draining requirements would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In accordance with one embodiment, a method for operating an appliance is provided. The method includes activating a drain pump to operate at a first speed, and ascertaining a dry drain status for the drain pump after a first speed drain time. The method further includes performing a deactivation routine when the dry drain status is positive, the deactivation routine comprising deactivating the drain pump. The method further includes performing a secondary drain routine when the dry drain status is negative, the secondary drain routine comprising activating the drain pump to operate at a second speed, the second speed greater than the first speed.

In accordance with another embodiment, a dishwasher appliance is provided. The dishwasher appliance includes a tub that defines a wash chamber for receipt of articles for washing, and a sump for collecting fluid from the wash chamber. The dishwasher appliance further includes a fluid circulation assembly in fluid communication with the sump, the fluid circulation assembly comprising a drain pump, and a control unit in communication with the drain pump. The control unit is operable for activating the drain pump to operate at a first speed, and ascertaining a dry drain status for the drain pump after a first speed drain time. The control unit is further operable for performing a deactivation routine when the dry drain status is positive, the deactivation routine comprising deactivating the drain pump. The control unit is further operable for performing a secondary drain routine when the dry drain status is negative, the secondary drain routine comprising activating the drain pump to operate at a second speed, the second speed greater than the first speed.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 provides a side cutaway view of a dishwasher appliance in accordance with one embodiment of the present disclosure;

FIG. 2 provides a schematic view of a fluid circulation assembly for a dishwasher appliance in accordance with one embodiment of the present disclosure; and

FIG. 3 provides a flow chart illustrating a method for operating an appliance in accordance with one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 depicts an exemplary dishwasher appliance 100 according to an exemplary embodiment of the present disclosure. However, it should be understood that the systems and methods disclosed herein are not limited to use with dishwashers as described herein, and rather that any suitable dishwasher appliance is within the scope and spirit of the present disclosure. Further, the present disclosure is not limited to dishwashers. Rather, use with other suitable appliances, such as washing machine appliances, is within the scope and spirit of the present disclosure.

The dishwasher appliance 100 can include a cabinet 102 having a tub 104 therein that defines a wash chamber 106. The tub 104 can include a front opening (not shown in FIG. 1) and a door 120 hinged at its bottom 122 for movement between a normally closed vertical position wherein the wash chamber 106 is sealed shut for washing operation, and a horizontal open position for loading and unloading of dishwasher contents. Upper and lower guide rails 124, 126 can be mounted on tub side walls 128 and can accommodate upper and lower roller-equipped rack assemblies 130, 132, respectively.

A lower spray-arm-assembly 144 can be rotatably mounted within a lower region 146 of the wash chamber 106 and above tub sump portion 142 so as to rotate in relatively close proximity to the lower rack assembly 132. A mid-level spray-arm assembly 148 can be located in an upper region of the wash chamber 106 and can be located in close proximity to the upper rack 130 and at a sufficient height above lower rack 132 to accommodate larger items, such as a dish or platter. In a further embodiment, an upper spray assembly can be located above the upper rack assembly 130 at a sufficient height to accommodate taller items in the upper rack assembly 130.

The lower and mid-level spray-arm assemblies 144, 148 and the upper spray arm assembly can be fed by a fluid circulation assembly for circulating water and dishwasher fluid in the tub 104. The fluid circulation assembly can be located in a machinery compartment 140 located below the bottom sump portion 142 of the tub 104, as generally recognized in the art.

Operation of the dishwasher 100 can be regulated by a control unit 137 which is operatively coupled to a user interface or input 136 for user manipulation to select dishwasher machine cycles and features. In response to user manipulation of the user interface 136, the control unit 137 can operate the various components of the dishwasher appliance 100 and execute selected machine cycles and features. The control unit may include one or more memory devices and one or more microprocessors, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a particular cycle of the dishwasher appliance 100. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

In one embodiment, the user interface 136 can represent a general purpose I/O (“GPIO”) device or functional block. In another embodiment, the user interface 136 can include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 136 can include a display component, such as a digital or analog display device designed to provide operational feedback to a user.

The control unit 137 can be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the control unit 137 is located within a control panel area of door 120 as shown. In such an embodiment, input/output (“I/O”) signals can be routed between the control system and various operational components of dishwasher 100 along wiring harnesses that can be routed through the bottom 122 of door 120.

Again, it should be appreciated that the method disclosed herein is not limited to any particular style, model, or other configuration of dishwasher, and that the embodiment depicted in FIG. 1 is for illustrative purposes only. Further, the present disclosure is not specifically limited to dishwashers, but can be implemented with respect to other appliances as well, including washing machine appliances.

FIG. 2 depicts an exemplary fluid circulation assembly 170 of the exemplary dishwasher of FIG. 1 according to an exemplary embodiment of the present disclosure. Although one exemplary embodiment of fluid circulation assembly 170 operable in accordance with aspects of the disclosure is shown, it is contemplated that other fluid circulation assembly configurations may similarly be utilized without departing from the spirit and scope of the invention.

Fluid circulation assembly 170 can include a wash pump 172 and a drain pump 174, both in fluid communication with sump 150. Additionally, drain pump 174 can be in fluid communication with an external drain 173 to discharge used wash liquid, e.g., to a sewer or septic system (not shown). Further, wash pump 172 can be in fluid communication with lower spray arm assembly 144 and conduit 154 which extends to a back wall 156 of wash chamber 106, and upward along back wall 156 for feeding wash liquid to mid-level spray arm assembly 148 (FIG. 1) and the upper spray arm assembly. This configuration also applies to a drawer-type of dishwasher, as mentioned above.

As wash liquid is pumped through lower spray arm assembly 144, and further delivered to mid-level spray arm assembly 148 and the upper spray arm assembly (not shown), washing sprays can be generated in wash chamber 106, and wash liquid can collect in sump 150. Sump 150 can include a cover to prevent larger objects from entering sump 150, such as a piece of silverware or another dishwasher item that is dropped beneath lower rack 132. A coarse filter and a fine filter (not shown) can be located adjacent sump 150 to filter wash liquid for sediment and particles of predetermined sizes before flowing into sump 150. Sump 150 can be filled with water through an inlet port 175 which outlets into wash chamber 106, as described in greater detail below.

A water supply 200 can be configured with inlet port 175 for supplying wash liquid to wash chamber 106. Water supply 200 can provide hot water only, cold water only, or either selectively as desired. As depicted, water supply 200 can have a hot water input 204 that receives hot water from an external source, such as a hot water heater and a cold water input 206 that receives cold water from an external source. It should be understood that the term “water supply” is used herein to encompass any manner or combination of valves, lines or tubing, housing, and the like, and may simply comprise a conventional hot or cold water connection.

As shown in FIG. 2, a drain valve 186 can be established in flow communication with sump 150 and can open or close flow communication between sump 150 and a drain pump inlet 188. Drain pump 174 can be in flow communication with drain pump inlet 188 and can include an electric motor for pumping fluid at inlet 188 to an external drain system via drain 173. In one embodiment, when drain pump 174 is operating, a negative pressure can be created in drain pump inlet 188 and drain valve 186 is opened, allowing fluid in sump 150 to flow into fluid pump inlet 188 and be discharged from fluid circulation assembly 170 via external drain 173.

Alternatively, drain and wash pumps 172 and 174 can be connected directly to the side or the bottom of sump 150, and drain and wash pumps 172, 174 can each include their own valving replacing drain valve 186. Other fluid circulation systems are possible as well, drawing fluid from sump 150 and providing fluid as desired within wash chamber 106 or draining fluid out of appliance 100.

In addition, fluid circulation assembly 170 can include one or more heating elements for heating water within the dishwasher. Generally, the heating elements can be used to heat water for use by wash pump 172 for one or more wash or rinse cycles in which the contents of the dishwasher are subjected to the heated water. In particular, in some embodiments, the one or more heating elements can be included internally within wash pump 172.

As shown in FIG. 2 and as discussed below, control unit 137 can communicate with and is operable to control the operation of wash pump 172, drain pump 174, drain valve 186, and water supply 200.

As discussed above, dishwasher appliances 100 and associated methods that provide a balance between quiet operation and complete drainage are desired. Accordingly, and referring now to FIG. 3, the present disclosure is further directed to methods 300 for operating appliances, such as dishwasher appliances 100, washing machine appliances, and other suitable appliances, which advantageously provide such balance. Additionally, dishwasher appliances 100 which include control units 137 that facilitate such balance are advantageously provided. It should be understood that control unit 137 may in exemplary embodiments be operable to perform the various method steps as disclosed herein.

Advantageously such methods 300 and appliances utilize drain pumps 174 which can be activated to operate at multiple speeds. In other words, the motor of such drain pumps 174 may operate at multiple speeds. In some embodiments, for example, a drain pump 174 may be operable at only two speeds. In other embodiments drain pump 174 may be operable at more than two speeds. In general, it is understood that the speed at which a pump operates is proportional to the power output of the pump. For example, a higher speed results in a greater power output. In the context of a drain pump 174, a higher speed can thus result in more efficient and/or complete draining Higher speeds would thus be desirable in environments which have undesirable draining conditions, caused for example, by blockages, small drain pipes, etc. Of course, a speed increase can also result in an increase in the noise produced by the pump when operating. The present methods and appliances advantageously balance these concerns.

Method 300 may thus include, for example, the step 310 of activating the drain pump 174 to operate at a first speed 312. The drain pump 174 may be activated as desired and as generally understood to facilitate draining of liquid from the dishwasher appliance 100 during appliance 100 operation. The first speed 312 may advantageously be a low speed, such as a speed lower than a second speed as discussed herein. Advantageously, operation at such low speed may provide generally desirable quiet operation.

Method 300 may further include, for example, the step 320 of ascertaining a dry drain status 322 for the drain pump 174 after a first speed drain time 324. In exemplary embodiments, the drain time 324 is a predetermined time period that is for example programmed into the control unit 137. The drain time 324 may begin, for example, when the drain pump 174 is activated in accordance with step 310, and may be a time period for draining before the dry drain status 322 is ascertained. The drain time 324 may or may not include pauses of various lengths of time to facilitate draining. Ascertaining the dry drain status 322 includes determining whether the draining operation of the drain pump 174 is complete by determining whether the drain pump 174 is generally dry. If the drain pump 174 is generally dry, the dry drain status 322 may be positive. If the drain pump 174 is not generally dry, and draining is thus still required, the dry drain status 322 may be negative.

Ascertainment of the dry drain status 322 may be accomplished in accordance with a variety of methods and/or apparatus, and is generally understood in the art. For example, in some embodiments, a pump inverter current may be monitored. For each instance in which the pump transitions from a wet state to a dry state or cavitation, the inverter current may demonstrate a detectable reduction in magnitude. Details of suitable methods and apparatus for such detection are provided in, for example, U.S. patent application Ser. No. 13/937,493 filed on Jul. 9, 2013 and entitled “Systems and Methods for Detecting Appliance Pump Cavitation or Dry State”, which is incorporated by reference in its entirety herein. Such reduction in magnitude may for example be utilized to detect a positive dry drain status 322. If, for example, when step 320 occurs it is ascertained that no reduction in magnitude has occurred during the first speed drain time 324, the dry drain status 322 may be negative. If, on the other hand, when step 320 occurs it is ascertained that a reduction in magnitude has occurred during the first speed drain time 324, the dry drain status 322 may be positive.

It should be understood that the present disclosure is not limited to such embodiments for ascertainment of the dry drain status 322, and rather that any suitable methods or apparatus are within the scope and spirit of the present disclosure.

In some cases, the dry drain status 322 may be positive. Accordingly, method 300 may further include the step 330 of performing a deactivation routine when the dry drain status 322 is positive. The deactivation routine may include, for example, the step 334 of deactivating the drain pump 174. In some embodiments, such deactivation may be performed immediately upon ascertainment that the dry drain status 322 is positive. In other embodiments, the deactivation routine may further include, for example, the step 336 of continuing operation of the drain pump 174 at the first speed 312 for a first speed extend time 338. In exemplary embodiments, the extend time 338 is a predetermined time period that is for example programmed into the control unit 137. Such first speed extend time 338 may be a time period that provides an additional delay before deactivating the drain pump 174, as a backup to ensure that the drain pump 174 is sufficiently dry before it is deactivated. The step 334 may thus in these embodiments occur after the step 336.

When the dry drain status 322 is positive as discussed above, this generally indicates that the first speed 312 is currently sufficient for draining purposes. Further, as discussed, such operation is advantageously at a relatively low noise level, such that drainage and noise concerns are balanced.

In other cases, the dry drain status 322 may be negative. Accordingly, method 300 may further include the step 340 of performing a secondary drain routine when the dry drain status 322 is negative. The secondary drain routine may include, for example, the step 350 of activating the drain pump 174 to operate at a second speed 352. The second speed may be greater than the first speed 312. Such second speed 352 may thus cause the drain pump 174 to produce relatively more noise than the first speed 312. However, the negative dry drain status 322 in these cases indicates that increased power output from the drain pump 174 may be necessary for drainage to be completed. Accordingly, activation at this point at the second speed 352 may balance drainage and noise concerns, which the drainage concerns at this point taking precedence.

The secondary drain routine may additionally include other steps which may serve to further evaluate and balance drainage and noise concerns. For example, the secondary drain routine may further include the step 360 of ascertaining the dry drain status 322 for the drain pump 174 after a second speed drain time 364. In exemplary embodiments, the drain time 364 is a predetermined time period that is for example programmed into the control unit 137. The drain time 364 may begin, for example, when the drain pump 174 is activated in accordance with step 350, and may be a time period for draining before the dry drain status 322 is ascertained. The drain time 364 may or may not include pauses of various lengths of time to facilitate draining.

In some cases, the dry drain status 322 may be positive. Accordingly, method 300 may further include the step 370 of performing a secondary deactivation routine when the dry drain status 322 is positive. The secondary deactivation routine may include, for example, the step 374 of deactivating the drain pump 174. In some embodiments, such deactivation may be performed immediately upon ascertainment that the dry drain status 322 is positive. In other embodiments, the deactivation routine may further include, for example, the step 376 of continuing operation of the drain pump 174 at the second speed 352 for a second speed extend time 378. In exemplary embodiments, the extend time 378 is a predetermined time period that is for example programmed into the control unit 137. Such second speed extend time 378 may be a time period that provides an additional delay before deactivating the drain pump 174, as a backup to ensure that the drain pump 174 is sufficiently dry before it is deactivated. The step 374 may thus in these embodiments occur after the step 376.

In other cases, the dry drain status 322 may be negative. Accordingly, method 300 may further include the step 380 of continuing operation of the drain pump 174 at the second speed 352 when the dry drain status 322 is negative and repeating the ascertaining step 360. Accordingly, after an additional second speed drain time 364, the dry drain status 322 for the drain pump 174 may again be ascertained. Step 380 may additionally then be repeated as required upon repeating step 360 if the dry drain status 322 is negative. When the dry drain status 322 is positive, such repetition may be discontinued, because step 370 (and associated sub-steps) may occur.

In some embodiments, the secondary drain routine may further include the step 400 of tallying consecutive occurrences 402 of the dry drain status 322 being negative. For example, a first occurrence may be tallied after step 320 when the dry drain status 322 is negative and step 340 generally occurs. Consecutive occurrences after this first occurrence may be tallied after step 360 when the dry drain status 322 is negative and step 380 occurs, such that step 360 is repeated.

Further, the secondary drain routine may include the step 410 of disabling activation of the drain pump 174 at the first speed 312 when the tally of consecutive occurrences 402 is greater than or equal to a consecutive occurrence threshold 412. In exemplary embodiments, the consecutive occurrence threshold 412 is a predetermined number that is for example programmed into the control unit 137. When the tally of consecutive occurrences 402 meets or exceeds the threshold 412, this generally indicates a drainage issue, such as a permanently slow drainage environment. In these cases, activation of the drain pump 174 at the first speed 312 is disabled, because the need for complete draining in an efficient manner takes precedence over the desire for quiet operation.

Secondary drain routine may further additionally include, for example, the step 420 of resetting the tally of consecutive occurrences 402 when a positive dry drain status 322 occurs. In exemplary embodiments, such resetting step 420 may only occur before step 410 occurs. Accordingly, an intervening positive dry drain status 322 may reset the tally of consecutive occurrences 402 to zero or a lesser number in the tally, such that the tally begins anew from zero or a new, lesser tally value upon the next operation of the drain pump 174 in accordance with the present disclosure. This allows operation of the drain pump 174 at the first speed 312 to be utilized again to attempt complete drainage, thus advantageously allowing quiet operation when complete drainage does occur before the consecutive occurrence threshold 412 is met to indicate the need for higher speed, higher power drainage and resulting increased noise.

Accordingly, the present disclosure advantageously provides methods 300 and dishwasher appliances which balance the needs for complete and efficient drainage with the desire for quiet operation in a variety of drainage scenarios.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A method for operating an appliance, the method comprising: activating a drain pump to operate at a first speed; ascertaining a dry drain status for the drain pump after a first speed drain time; performing a deactivation routine when the dry drain status is positive, the deactivation routine comprising deactivating the drain pump; and performing a secondary drain routine when the dry drain status is negative, the secondary drain routine comprising activating the drain pump to operate at a second speed, the second speed greater than the first speed.
 2. The method of claim 1, wherein the deactivation routine further comprises continuing operation of the drain pump at the first speed for a first speed extend time, and wherein deactivating the drain pump occurs after continuing operation of the drain pump at the first speed for the first speed extend time.
 3. The method of claim 1, wherein the secondary drain routine further comprises ascertaining the dry drain status for the drain pump after a second speed drain time.
 4. The method of claim 3, wherein the secondary drain routine further comprises performing a secondary deactivation routine when the dry drain status is positive, the secondary deactivation routine comprising deactivating the drain pump.
 5. The method of claim 4, wherein the secondary deactivation routine further comprises continuing operation of the drain pump at the second speed for a second speed extend time, and wherein deactivating the drain pump occurs after continuing operation of the drain pump at the second speed for the second speed extend time.
 6. The method of claim 3, wherein the secondary drain routine further comprises continuing operation of the drain pump at the second speed when the dry drain status is negative and repeating the step of ascertaining the dry drain status for the drain pump after a second speed drain time.
 7. The method of claim 6, wherein the secondary drain routine further comprises tallying consecutive occurrences of the dry drain status being negative.
 8. The method of claim 7, wherein the secondary drain routine further comprises disabling activation of the drain pump at the first speed when the tally of consecutive occurrences is greater than or equal to a consecutive occurrence threshold.
 9. The method of claim 6, wherein the secondary drain routine further comprises resetting the tally of consecutive occurrences when a positive dry drain status occurs.
 10. A dishwasher appliance, comprising: a tub that defines a wash chamber for receipt of articles for washing; a sump for collecting fluid from the wash chamber; a fluid circulation assembly in fluid communication with the sump, the fluid circulation assembly comprising a drain pump; and a control unit in communication with the drain pump, the control unit operable for: activating the drain pump to operate at a first speed; ascertaining a dry drain status for the drain pump after a first speed drain time; performing a deactivation routine when the dry drain status is positive, the deactivation routine comprising deactivating the drain pump; and performing a secondary drain routine when the dry drain status is negative, the secondary drain routine comprising activating the drain pump to operate at a second speed, the second speed greater than the first speed.
 11. The dishwasher appliance of claim 10, wherein the deactivation routine further comprises continuing operation of the drain pump at the first speed for a first speed extend time, and wherein deactivating the drain pump occurs after continuing operation of the drain pump at the first speed for the first speed extend time.
 12. The dishwasher appliance of claim 10, wherein the secondary drain routine further comprises ascertaining the dry drain status for the drain pump after a second speed drain time.
 13. The dishwasher appliance of claim 12, wherein the secondary drain routine further comprises performing a secondary deactivation routine when the dry drain status is positive, the secondary deactivation routine comprising deactivating the drain pump.
 14. The dishwasher appliance of claim 13, wherein the secondary deactivation routine further comprises continuing operation of the drain pump at the second speed for a second speed extend time, and wherein deactivating the drain pump occurs after continuing operation of the drain pump at the second speed for the second speed extend time.
 15. The dishwasher appliance of claim 12, wherein the secondary drain routine further comprises continuing operation of the drain pump at the second speed when the dry drain status is negative and repeating the step of ascertaining the dry drain status for the drain pump after a second speed drain time.
 16. The dishwasher appliance of claim 15, wherein the secondary drain routine further comprises tallying consecutive occurrences of the dry drain status being negative.
 17. The dishwasher appliance of claim 16, wherein the secondary drain routine further comprises disabling activation of the drain pump at the first speed when the tally of consecutive occurrences is greater than or equal to a consecutive occurrence threshold.
 18. The dishwasher appliance of claim 15, wherein the secondary drain routine further comprises resetting the tally of consecutive occurrences when a positive dry drain status occurs.
 19. The dishwasher appliance of claim 10, wherein the drain pump is a two-speed drain pump.
 20. The dishwasher appliance of claim 10, wherein the fluid circulation assembly further comprises a wash pump. 